Types

Endocrine Disruptors

INTRODUCTIONEndocrine disruptors have been linked to various cancers, damage to the immune system and many reproductive health problems.

Some have been termed “gender-benders” as they are thought to damage reproductive organs and fertility, or alter the sex ratio of offspring, as has been observed in many species (humans included).

The main evidence for these effects comes from studies of wildlife or of laboratory animals that scientists have exposed to known amounts of suspected endocrine disruptors.

More recent research has connected specific chemicals to health impacts in human populations.

Concerns about endocrine disruptors have led to calls for tighter regulations or bans of these chemicals. Some scientists and industry bodies argue however that there is no solid evidence of a real problem.

Endocrine disruptors are thought to interfere with hormones, the natural chemical messengers that regulate the functions of our cells and organs.

Some, for instance, are thought to disrupt the male sex hormone androgen or mimic the female sex hormone oestrogen.

This poses special risks to young boys and has been linked to genital deformities, testicular cancer and reduced sperm counts.

People are most at risk if they are exposed to endocrine disruptors in the womb or in early childhood when their bodies are still developing.

There are hundreds of known or suspected endocrine disruptors. They include animal hormones, plant chemicals, pesticides, and compounds including phthalates and PBDEs from industrial and consumer products.

In addition, some governments have banned or controlled the use of some of these chemicals, however most are unregulated, especially in developing nations.

Some endocrine disruptors can persist in the environment by accumulating in soils and marine or river sediments. Such sites can sometimes be cleaned up – or remediated – but this can be very costly and take a long time.

Methods for remediation include using high-tech equipment and using biological processes, such as plants or microbes that absorb pollutants and break them down into safe compounds.

A big challenge for reporters is the difficulty of saying for certain that a health effect is definitely due to exposure to a particular chemical. Proving that link is almost impossible, even if the chemical is a known endocrine dispruptor.

Journalists should also be aware of national and international laws controlling these substances.

The websites of the Stockholm Convention or the Rotterdam Convention are good sources of information on current and proposed controls, and contact details of relevant authorities in each nation.

Journalists need speak to these and other sources, including activists, health professionals and the chemical industry.

Many of the early studies about endocrine disruptors were summarised in a book called Our Stolen Future, whose authors’ website includes a page on media coverage of “myths and realities” about these chemicals.

Increasing awareness of these risks has led people to urge governments to adopt the precautionary principle, and regulate suspected endocrine disruptors even if there is not strong scientific evidence of harm.

Critics such as industry groups argue that this is unnecessary and point out that many naturally occuring chemicals in plants can also mimic human hormones.

For an analysis of how the media has covered these competing viewpoints, see this article.

SourceWatch includes listings of organisations that have commented publically on endocrine disruptors from both sides of the debate.

CASE STUDY – Skewed sex ratiosScientists have recently been reporting declines in male births worldwide, but this is particularly extreme than among the Aamjiwnaang First Nation community in Sarnia, Canada.

It also showed that the community land was highly polluted. However, the researchers pointed out that is it hard to assess whether a single compound causes an adverse effect, adding that the community may have had multiple chemical exposures over the years.

The fact that some endocrine disruptors in the areas could be persistent organic pollutants that have travelled thousands of kilometres makes it even hard to say for sure what is causing the observed effects.

This story shows the challenges of reporting on endocrine disruptors and attributing observed effects to a specific source. To read how journalist Terri Hansen covered it, visit her blog.

Judith Graham, writing in the Chicago Tribune, wrote a more in-depth piece that showed how sex ratios are also changing elsewhere and included some alternative explanations.

For case studies of specific endocrine disruptors, see the toolkit pages on Bisphenol A, PBDEs and dioxin and PCBs.